Hydraena confluenta, Perkins, 2011

Perkins, Philip D., 2011, New species (130) of the hyperdiverse aquatic beetle genus Hydraena Kugelann from Papua New Guinea, and a preliminary analysis of areas of endemism (Coleoptera: Hydraenidae) 2944, Zootaxa 2944 (1), pp. 1-417 : 110-111

Hydraena confluenta , new species

( Figs. 195 , 197 , 526 )

Type Material. Holotype (male): Eastern Highlands Province: Umg. [=environs of] Kainantu, Onerunka , [GE est.] 1500–1700 m, 6° 17' S, 145° 52' E, 1–30 iii 1980, W. G. Ullrich ( MHNG).

Differential Diagnosis. Similar in color and dorsal sculpture to H. processa ( Figs. 195 , 198 ); differing therefrom by the larger size (TL ca. 1.63 vs. 1.48 mm), the slightly narrower body form (EW/TL ca. 0.44 vs. 0.47), the wider mesoventral intercoxal process (P2), the more widely spaced plaques (plaque ratios ca. 6/1/5/8 vs. 5/1/5/7), and the confluently concave AIS and first abdominal ventrite. The general plan of the male genitalia of the two species also suggests a relationship, but the genitalia distinctively differ in details, and should be examined for reliable determinations ( Figs. 197 , 200).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.63/0.72; head 0.28/0.37; pronotum 0.38/0.52, PA 0.40, PB 0.44; elytra 0.97/0.72. Dorsum dark reddish brown, frons darkest, clypeus and labrum lightest; legs reddish brown; maxillary palpi testaceous, tip not darker.

Frons punctures ca. 1–2xef, larger and denser near eyes than medially; interstices shining, 1–3xpd. Clypeus microreticulate laterally, very finely sparsely punctate medially. Mentum and postmentum very sparsely very finely punctulate, shining. Genae raised, shining, without posterior ridge. Pronotum subcordiform, ca. median 3/4 of anterior margin arcuate to posterior; punctures on disc slightly smaller than smallest frons punctures, interstices shining, 2–4xpd, punctures larger and denser at anterior and posterior; disc slightly longitudinally convex; PF1 very shallow, obsolete; PF2 shallow, medially confluent, forming U-shaped impression; PF3 deep; PF4 absent or very shallow.

Elytra with summit of posterior declivity at or very near midlength; lateral explanate margins rather wide; on basal 1/3 punctures ca. 1xpd largest pronotal punctures, a few punctures subserial, punctures becoming gradually smaller toward posterior. Intervals not raised, shining, on disc ca. 2–3xpd, as are interstices between punctures of a row. Apices in dorsal aspect conjointly rounded, in posterior aspect margins forming shallow angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 6/1/5/8. P1 ca. 2/3 P2; median carina bisinuate in profile. P2 transversely slightly concave, l/w ca. 5/6, sides slightly diverging toward blunt apex. Plaques very narrow, carinate, converging slightly anteriorly, at sides of deep median depression. Metaventrite concave between P2 and plaques. AIS conjointly concave with anteromedial area of first ventrite, width at straight posterior margin ca. 1.3x P2. All legs moderately long and slender. Profemur (male) with small tubercle next to trochanter; protibia slightly arcuate, anterior margin very slightly widened subapically, medial margin flat except small sharp tubercle subapically on posteromedial margin. Meso- and metatibia straight. Abdominal apex symmetrical; last tergite (male) deeply notched. Aedeagus as illustrated ( Fig. 197 ).

Etymology. Named in reference to the confluently concave AIS and first abdominal ventrite.

Distribution. Currently known only from the type locality near Onerunka, in the eastern part of Area 1, where it borders Area 2; elevation 1500–1700 m ( Fig. 526 ).

Figures

FIGURE 195. Hydraena confluenta, holotype, dorsal and lateral habitus, and venter.

FIGURE 198. Hydraena processa, holotype, dorsal and lateral habitus, and venter.

FIGURES 196–197. Aedeagi of holotypes. 196. H. pacificica. 197. H. confluenta.

FIGURES 523–526. Geographical distributions of Hydraena species.